Vulnerabilities
Misconfiguration
Compliance
CVE Vulnerabilities

CVE-2026-50257

Use After Free

Published: Jun 05, 2026 | Modified: Jun 25, 2026
CVSS 3.x
N/A
Source:
NVD
CVSS 2.x
RedHat/V2
RedHat/V3
7.8 IMPORTANT
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Ubuntu
MEDIUM
Vulnerability-free packages from our partners
root.io logo minimus.io logo echo.ai logo
Additional information
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2026-50257
CWEhttps://cwe.mitre.org/data/definitions/416.html

A use-after-free flaw was found in the X.Org X server and Xwayland in miSyncDestroyFence(). A client that sets up multiple fence triggers can trigger a use-after-free function pointer call. An attacker would connect to the X server to set up a fence and await that fence, then a second X connection destroys the fence, causing the use-after-free. This may be used to crash the server, or for privilege escalation if the X server runs as root.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

NameVendorStart VersionEnd Version
X_serverX.org*21.1.23 (excluding)
XwaylandX.org*24.1.12 (excluding)
Enterprise_linuxRedhat7.0 (including)7.0 (including)
Enterprise_linuxRedhat8.0 (including)8.0 (including)
Enterprise_linuxRedhat9.0 (including)9.0 (including)
Enterprise_linuxRedhat10.0 (including)10.0 (including)
Red Hat Enterprise Linux 10RedHatxorg-x11-server-Xwayland-0:24.1.9-4.el10_2.2*
Red Hat Enterprise Linux 8RedHatxorg-x11-server-Xwayland-0:21.1.3-20.el8_10.2*
Red Hat Enterprise Linux 8RedHatxorg-x11-server-0:1.20.11-28.el8_10.2*
Red Hat Enterprise Linux 8RedHattigervnc-0:1.15.0-10.el8_10*
Red Hat Enterprise Linux 9RedHatxorg-x11-server-Xwayland-0:24.1.9-4.el9_8.2*
Red Hat Enterprise Linux 9RedHatxorg-x11-server-0:1.20.11-34.el9_8.2*
Red Hat Enterprise Linux 9RedHattigervnc-0:1.15.0-7.el9_8.2*
XwaylandUbuntuupstream*

Potential Mitigations

References

Aqua Security is the largest pure-play cloud native security company, providing customers the freedom to innovate and run their businesses with minimal friction. The Aqua Cloud Native Security Platform provides prevention, detection, and response automation across the entire application lifecycle to secure the build, secure cloud infrastructure and secure running workloads wherever they are deployed.
Copyright © 2026 Aqua Security Software Ltd.   Privacy Policy | Terms of Use